Next year scientists hope to trigger a fusion reaction with its
192 lasers

By Jenny Mandel
August 20, 2009

Federal researchers are slowly testing 192 lasers
that they hope will set off the world's first controlled nuclear fusion
reaction.

The lasers are housed at the National Ignition
Facility (NIF), a $4 billion complex the size of three football fields
that is part of the Lawrence Livermore National Laboratory in Livermore,
Calif.

The facility's construction was completed this spring
with tests directing more than a megajoule of energy at a target (a
megajoule is the energy consumed by 10,000 100-watt light bulbs in a
second). Now researchers are preparing for a first use of its full
capabilities next year, when the battery of lasers will be trained on a
small pellet of fuel in hopes of igniting it to trigger a brief but
powerful fusion reaction.

While commercially operating nuclear fission reactors
provide power -- and a host of controversy over weapons use and waste
disposal -- nuclear fusion is a different process. A sustained string of
uncontrolled fusion reactions can be used for military purposes such as
a hydrogen bomb, and since the 1950s, scientists have chased controlled
fusion reactions for potential civilian purposes.

NIF will offer them new opportunities to study the
process in a laboratory setting.

Preparation for the big experiment next year involves
gradually running the lasers at higher intensities. The team is wary of
moving too fast for fear of seeing a dramatic flop like the one that
happened with a similar project in Switzerland in September 2008.

The Large Hadron Collider, a massive European
facility that runs similar experiments on superheated matter, was
sidelined by engineering problems just days after it opened.

So the facility's scientists are working cautiously.
"We don't want to break the world's biggest laser in its first
month of operation," NIF researcher Mordecai Rosen said in an
interview yesterday at the American Chemical Society's annual meeting in
Washington, D.C.

Late next year, Rosen said, the full power of the
lasers will be trained on a fuel capsule the size of a pea. The
resultant implosion is expected to generate 10 times as much energy as
was used to power the machines.

Rosen said the facility will provide new
opportunities for astrophysicists to study the stars and other matter,
and for nuclear scientists to run experiments that could eventually lead
to fusion power production. Some classified work related to the U.S.
nuclear stockpile will also be done there, according to Tom D'Agostino,
administrator of the Energy Department's National Nuclear Security
Administration, which runs the lab.

One unique element of the Livermore facility is that
it provides a view into the behavior of hot, highly pressurized matter,
whereas the Large Hadron Collider works with heat but not high
density.

Rosen likens the NIF apparatus to a giant microwave
with a baked potato inside.

Next year, the microwave will be heated to 3 million
degrees. What happens to the potato remains to be seen.